1. Field of the Invention
The present invention relates to a permanent magnet type (PM type) stepping motor.
2. Description of Related Art
A stepping motor can be used for driving, e.g. a print head or a platen roll of a printer. A stepping motor of this type is disclosed in U.S. Pat. No. 4,990,806. The PM type stepping motor comprises in general coils wound around pole pieces, ring-shaped stators and a rotor composed of a permanent magnet disposed at the central portion of the stators.
In conventional PM type stepping motor a problem exists in that the drive efficiency of the motor is decreased because of eddy currents and heat generation caused by Joule heating occurred.